System for cooling mines and other chambers requiring ventilation



June 1 1, 1929- w. H. CARRIER SYSTEM FOR COOLING MINES AND OTHER CHAMBERS REQUIRING VENTILATION Patented `lune ll, 1929.

UNITED STATES PATENT OFFICE.

WILLIS H. CARRIER, 0F ESSEX FELLS, NEW JERSEY, ASSIGNOR TO CARRIER ENGI- NEERING CORPORATION, OF NEWARK, NEW JERSEY.

SYSTEM FOR COOLING MINES ANI) OTHER CHAMBERS REQUIRING VENTILATION.

Application filed February 25, 1924, Serial No. 695,045, and in Great Britain July 2, 1923.

A diflicult problem is encountered in cooling deep mines when the depth of a mine reaches 5000 ft. or more. Not only are the rock temperatures liigln'increasing about 1 degree for every 200 feet-but the air delivered down into the mine is--heated up by compression. rThis natural heating due to adiabatic compression through increased barometric pressure would amount to nearly 300 for a depth of 5000 below the surface.

In addition to this, there is a large quantity of moist-ure absorbed from water in the mine and from the rocks so that the degree ot saturation is frequently as great, or even greater, than at the surface. This means a great increase in moisture content and a correspondingly greater rise in the wet bulb temperature which indicates the tot-al heat present. in the air.

Large volumes of air are required for ventilation of a deep mine because of the high rock temperatures which make it impossible to work such a mine without ample ventilation, and as the depth of the mine increases, the value of such ventilation becomes less and less for the r lasons just pointed out.. In fact, at a depth of 5000 to 6000' the temperatures have reached the limit of human endurance.

l-leretofore, attempts have been made to reduce the temperatures in the lower workings by supplying thereto air cooled at the surface and removing the moisture to as low a point as possible. The effect of this has been to lower the temperature of the air somewhat in the mine, but. more particularly to lower its moisture content and has made it possible to -work such ar mine down to a level as low as 6000 even in warm climates. The effectiveness of such cooling is obviously1 largely lost by reason of the great transmission of heat to the air owing to the greater temperature difference, so that the cooling effect at the bottom of the mine is in no way proportionate' to the cooling eflfutat, the surface.

As the depth of the workings are increased. the cooling at the surface becomes of less and less value owing to the fact of the greater increase in temperature due to adiabatic compression and to the closer approximation of the air temperature to the rock temperature with increased length of the air-ways.

The obvious method. it it were practicable, would beto cool the air` not at the surface. but in the workings near the point where'the air is to be used and, at the same time, to remove thel moisture. ()nc means of thus cooling the air would be either wate l'at atmospheric temperature or artificially cooled water, or brine pumped down into the mine and then pumped back to the surface. The pressure on the pipes and cooling apparatus at such depths would become so excessive as to be impracticable in view of the enormousl strength of the materials required to stand such pressures, and also would be very excessive. in the consuml'itioiro l power due to the costI of pumping' the la rge quantities of cooling liquid required from th;` depth of the lower levels to the surface. i

The proposition which I prefer is that of placing the refrigerating equipment in the mine, and which is made entirely practicable by the application of my improved system of centrifugal refrigeration operated at pressures below atmospheric pressure, thus avoiding all dangers attendanton such procedure. The problem then is still not fully solved bccause it is manifestly as impraeticable to remove the heat from the condenser of the refrigerating apparatus by means of water at such depths as it would be to cool the air direct. However, I make use of thel principle of refrigeration which enables me to transfer heat from a lower temperature level to a higher temperature level. This is accomplished in a manner coordinated withthe existing ventilating systen'i so as not to interfere with it and. in fact, so as to largely supplant the need of mechanical apparatus, such. as fans, for supplyingr the air for ventilation as will hereafter be explained.

This systen'i comprises the application of a spray type of heat interchanger for cooling and dehumidifying the air entering the workings in which the air is brought into direct contact with a spray of artificially cooled water, however, a surface type of heat intel'- changer may be used if desired. although the effectiveness of heat transfer of the latter would be less. On this account, as well as for the reason that the water vapor condensed will be returned directly to' the circulating liquid. the spray system is preferably used.

Preferably, only a portion of the total air entering the workings is directly cooled and dehumidified. and this is cooled to a lower' temperature and lower moisture content than that ofthe air necessary in the workings. and the cooled portion of the air is then mixed with the remaining portion of the air supplied to give an unsaturated mixture at the temperature desired.

The corresponding heat to be removed from the condenser of the refrigerating equipment is taken care of through a spray type of heat interchanger placed in the outgoing air passage from the mine and through which the air passes in leaving the workings. In this heat interchanger the circulating condenser water is cooled primarily by evaporation and the air leaves the inter-changer at a condition of saturation at a slightly higher temperature than it leaves the workings. Thus the heat removed from the air entering the workings is directly transferrtal to the air leaving the workings. The effect of the corresponding higher temperature in the outgoing air is to greatly decrease its density below what it would be under natural ventilation. This produces a column of outgoing air which is much lighter than that 0f the incoming air, thus producing a strong` 11p-draft Which is either suflicient., or nearly sufficient, to cause the flow of air necessary for ventilation without. other means of air propulsion.

The system thus comprises two primary circuits of heat interchange; the first in which the water passes though the cooler of a refrigerating machine and then through a heat inter-changer, preferably of a spray type, whiclrabsorbs the sensible and latent heat from the moist air entering the working. In the second system of heat interchange, the water passes through the condenser where the latent heat of the refrigerant is absorbed and then through a spray type of heat interchanger in which the condenser Water is again cooled through a process of heat transfer and in cont-act with the current of the outgoing air. In both eases, means of water elimination are preferably provided to prevent the water being carried beyond the points desired so that it may be retained in the respective systems. So then it is evident that there will be a continuous.accumulation of water in the first system due to condensation from the air. and a. continuous loss of water in the second system due to evaporation of water into the air. The water acculumating in the fir-t s vsten'i can be used to advantage as makeup water forthe second system so that only a small additional quantity of make-up water is required for the second system for the condenser water. The small amount of additional make-up water can be supplied from the mine water. or from the surface if necessary. It is evident that these two sys'- tcnis operate interdependently, merely removing the heat from the air at the entrance point and transferring it 'and adding it to the air at the leaving point after the air has yperformed its function of cooling the mine workings and maintaining therein Ythe desired working temperature.

Another import-ant feature of this invention is the method whereby a portion only of the air is cooled and dehumdified and then mixed with the remaining portion entering the workings in such a way as not to interfere with the normal opera-tion of the ventilating system and, at the same time, provide a thorough air mixture having a dew point, or saturation temperature, which is cmisiderably lower than the dry bulb temperature of the mixture. ln other words, to provide a minimum wet bulb temperature, upon which the sense of bodily comfort depends, without an excessive lowering of the dry bulb temperature which would result in an excessive rate ot' heat transfer from the mine to the air. This reduction of the wet bulb temperature, without an excessive reduction of the dry bulb temperature, is important because it avoids the danger of rock explosions which occur in mines where air of too low a temperature is suddenly brought. into contact with the rock, and also avoids undue chilling l of the workers i-n the air-.ways

l.referahly the cooling apparatus and the fan for drawing the air through the same are placed in a chamber connected into a lby-pass parallel with the main air-way. This draws a portion of theV air through the apparatus and discharges it through a nozzle into an aspirating tube forn'iing a portion of the bypass which causes an additional quantity of air to be drawn through the by-pass and discharged again into thel main air-way after mixture with the cooled air. This avoids any direct contact'of the air at low teniperatures with the rock, or with people passing through the main air-way.

This arrangement. has great. practical importance as it avoids the use of any deflectors or air locks in the main air-way, therefore it interferes in no way with its normal use for the passage of the workers and the handling of the ore.

'lhe accompanying drawing is a diagrammatic illustration of an apparatus embodying my invention` suitable for performing the method hereinlwfore described.

ln said drawing, l represents an air-way or chamber ol' the mine workings. and Q and 3 indicate respectively the air inlet and exit shafts or passages which comi'nunicate with the mine or chamber so that air entering through the inlet passage will pass throughl llt) lill) l and the bypass 4, the dehumidifier being so arranged that the fan draws a portion only of the air from the inlet passage through the dehumidifier While another portion of the air can pass around or outside of the dehumidifier. The nozzle 7 and by-pass passage 4 form an aspirator or ejector whereby the discharge of the air through the nozzle 7 acts to draw a portion of the entering air around the dehumidifier and cause it to pass through the bypass passage and thoroughly mix therein with the dehumidified and cooled air from the dehumidifier.

9 represents the heat interchanger or cooler for the condenser Water of the refrigerating apparatus. This interclianger is arranged so that the air passing from the mine'workings or air-way 1 to the exit passage 3 will flow through the interchanger 9.

10, 11 and 12 represent respectively the cooler or evaporator, the centrifugal compressor and the condenser of the refrigerating apparatus for cooling the water which is used in the dehumidifier 5 for cooling the incoming air. A suitable volatile refrigerating medium is employed in the refrigerating apparatus, the refrigerant being vapor-ized in the evaporatoi 10 by heat abstracted from the water, the refrigerant vapor being withdrawn from the evaporator, compressed and delivered by the compressor 11 to the condenser l2 in which the vaporized refrigerant is condensed, and the liquefied refrigerant being returned to the evaporator in the usual cycle of operations.

13 represents a water circulating pump which is connected by pipes 14, 15 and 16 with the dehumidifier 5 and the evaporator l0 in a closed Water circulating system, so that the pump delivers the water, which is cooled in the evaporator 10, to the spray nozzles 17 of the dehiunidifier and returns the spray water. which collects in the bottom of the dehumidifier, back to the evaporator. The Water is thus recirculated in a closed ciicuit or system and used over and over, together with such additional water as is condensed from the air in the dehumidifier. The dehumidifier is provided in i'ear of the water spray nozzles with a. water eliminator, preferably consisting of a multiplicity of spaced Zig-zag vertical plates 18. The air, after passing through the water spray, flows through the zig-zag spaces between these eliminator plates, which act to separate the entrained free water from the air so that the air is discharged by the fan from the dehumidifier without entrained or free water.

Similarly, the condenser 12 of the refrigerating apparatus and the intel-changer or cooler 9 for the condenser water are connected in a closed water circulating system by pipes 19, 20 and 21 and a pump 22 which delivers warm water from the condenser 12 to the spray nozzles 23 of the intcrchanger 9 and by the air leaving the mine workings through the cooler or interchanger 9 cools the water,

' and the cooled water is returned to the condenser 12 for condensing the refrigerating medium in the refrigerating apparatus.

The operation of the apparatus will be understood from the foregoing description of the method.

I claim as my invention:

1. The herein described method of cooling mines and other chambers comprising the following steps; cooling air by refrigeration in or near the mine or chamber to be cooled. supplying the air thus cooled to the mine or chamber for cooling the latter, and transferring the heat removed from said entering air to the air which leaves the mine or chamber after performing its function of cooling the mine or chamber, thereby decreasing the density of the leaving air and promoting the upward movement of the same from the mine or cham- Der.

2. A method of cooling mines .and other chambers, which comprises cooling entering air by refrigeration in or near the chamber to be cooled, supplying the air thus cooled to the chamber for cooling the latter, and utilizing the outgoing air to cool the condensing medium used inthe refrigeration, whereby the exit of the used air Will be facilitated by its increase in temperature.

3. A method of cooling mines and other chambers, which comprises cooling the entering air by a cold circulating medium, refrigerating the cold medium, and transferring heat from the refrigerating operation to the outgoing air.

4. A method of cooling mines and other chambers having an air inlet and an air outlet at spaced points, which comprises refrig erating entering air to remove a portion of its moisture, conducting it to said chamber, subjecting the outgoing air to a continuous spray of a fluid medium. and using the latter as a cooling medium for the refrigerating operation. whereby the outgoing cool air in cooling the fluid medium and thus assisting 11i the refrigerating operation, will be heated therebv to facilitate its exit from the chamber.

i 5. The method of cooling mines and other chambers having an air inlet and an air outlet at spaced points, which comprises subjecting entering air to a. spray of a cooling medium to cool the same and remove part of its moisture, admitting such treated air to the chamber` subjecting the outgoing air to a spray of a liquid to lieatthe same and cause a cooling of the liquid, and refrigerating said cooling medium by utilizing for cooling purposes in connection therewith the liquid which is cooled by the outgoing air.

6. The method ot cooling mines and other chambers having an air inlet and an air outlet at spaced points, which comprises refrigerating ingoin g air to remove part of its moisture, admitting such refrigerated air to the chamber, transferring the heat of refrigeration to the outgoing air by spraying a liquid used for cooling purposes inthe refrigeration into the outgoing air, and making up the losses of evaporation in the last mentioned liquid from the liquid removed from the entering air during its refrigeration.

7. The method of cooling mines and other chambers having an air inlet and an air outlet, which comprises subjecting ingoing air to direct contact with a spray of a cold liquid to cool the same, removing the free moisture from the treated air, admitting the treated air to the chamber, ret'rigerating the liquid, and transferring heat of refrigeration to the outgoing air.

8. The method of cooling mines and other chambers having an air inlet and an air outlet, which comprises subjecting entering air to direct contact with a spray o't a cold liquid to cool the air, eliminating the tree n'loisturc from the air, admitting the treated air to the chamber for passage therethrough, Subject ing the outgoing air to direct contact with the sp ay of another liquid, removing the free moisture from the air subjected to the last mentioned liquid, and cooling said cold liquid by utilizing the cooling eti'ect of the outgoing air upon the second liquid.

9. The method of -cooling mines and other chambers having an air inlet and an air outlet, which comprises subjecting ingoing air at a. point in said chambers, adjacent the base ofthe incoming air shaft to the cooling action of centrifugal refrigeration operating at pressures below atmospheric pressure, and utilizing the cooling etliect ofthe outgoing air as an aid in the refrigeration of the ingoing air.

10. The method of treating the air of chambers of mines and the like, which comprises refrigerating at a point adjacent the 'entrance to the chamber to be treated, a portion only of the ingoing air to cool and dehumidify it to a lower temperature and a lower moisture content than desired for the air used in said chamber, and then mixing this air with the remaining portion of the ingoing air.

11. The method of treating the air of chambers of mines and the like, which cornprises refrigerating at a point adjacent the entrance to the chamber to be treated, a portion only of the ingoing air to cool and dehumidify it to a lower temperature anda lower moisture content than desired :tor the air used in said chamber, then mixing this air with the remaining portion of the ingoing air, and utilizing the cooling etl'ect ot the outgoing air in cooling the ingoing air.

12. rl'he method of treating air oit chalnbers otl mines and the like, which comprises cooling a portion only ot' the ingoing air at a point adjacent the entrance. to the chambers, and discharging'it in a manner to produce an aspirating action which will lause a 'liow ol and mixture .with zulditional ingoing uncooled air.

13. A method ot treating thi` air of cham- .bcrs otl mines and the 'like` which comprises cooling air entering said chamber at. a point adjacent the entrance to the chamber by refrigeration, and utilizingl the heat of the refrigeration to heat the outgoing air, whereby the outward movement ot the air is facilitated and the outgoing air is utilized in absorbing the heat of refrigeration.

14. A method oit' treating Ventilating air ot' mine chambers and the like having inlet and outlet conduits comuiunicating .with the chamber at spaced points thereof, and through which air is supplied to and removed from the chamber, said method comprisingby-passing a quantity of the lentering air at a point adjacent the entrance to the chamber, cooling part of this by-passed air, mixing it with the remainder of the bypassed air, and commingling the by-passed air with the other entering air.

15. Apparatus .tor treating air of chambers of mines and the like, which comprises a heat interchanecr in the path of ingoing air, a second heat interchanger in the path ot' outgoing air at a point adjacent the entrance to the chamber, and refrigerating means connected to both ot said heat interchangcrs for cooling ingoing air by said iii-st interchanger,and dissipatingl the heat generated b v the operation ot the retrigerating means to the outgoing air through said second interchanger.

1G. Apparatus for treating air of mine chambers and the like, which comprises a heat interchangcr, means for supplying a cooling medium to said heat interchanger, means for drawing a portion of the chamber air through said heat interchanger and discharging it iu a manner to produc-e an aspirating action and dravf` and mix with it uncooled air.

f 17. Appa 'atus for treating the air ot mine chambers and the like, which comprises a liquid spray cooler and dehumidifier in a position to treat ingoing air, means for circulating a liquid through said cooler and dehumiditicr to supply the spray therefor. an evaporator for cooling said liquid. means 1`or compressing a refrigerating medium and supplying it to said evaporator for evapo ration to cool said first liquid. a condenser tor Cooling the compressed refrigerating medium llt) before it is admitted to said evaporator, and means including a heat interchanger in the path of outgoing air for .cooling'said condenser.

18. Apparatus for treating air of mine chambers and the like having a descending air inlet shaft and an ascending air outlet shaft, which comprises a heat interchanger adjacent the bottom of the inlet shaft for cooling ingoing air, and refrigerating means for supplying cooling means to said heat interchanger, and a second heat interchanger adjacent the bottom of the air outlet shaft and connected to said refrigerating means for utilizing the cooling eifect of the outgoing air as an aid in the refrigeration of said cooling liquid.

19. Apparatus for treating air of mine chambers and the like, which comprises means for subjecting ingoing air to a spray of a cold liquid to cool and dehumidify -said air, removing the free moisture from said cooled air, means forspraying a liquid into outgoing air, including means for circulating the liquid forming the spray, means for removing and returning to the last mentioned circulating liquid the free moisture in the outgoing air leaving said second spray, and refrigerating means for cooling the liquid supplied to the spray used in treating the ingoing air and utilizing the cooling effect of the outgoing air upon the second liquid, whereby the free moisture removed from the cooled ingoing air maybeused to supply the losses by evaporation of the second liquid caused by the outgoing air.

20. Apparatus for treating Ventilating air of mine chambers and the like, which comprises a cooling device, means for drawing a portion of the ingoing air through the cooling device and discharging'it in a manner to produce an aspirating action and draw and mix with it uncooled air, and means for conducting this mixture to the chamber.

WILLIS H. CARRIER. 

